Insulin infusions are increasingly being used in very low birth weight (VLBW) infants to "promote growth". The first objective of this study is to determine the effect of insulin infusion on proteolysis in the VLBW infant. To date, no studies have addressed this question in VLBW infants and it remains unclear if insulin is actually sparing protein breakdown or merely increasing lipid accretion. Contrary to current thinking, VLBW infants have recently been shown to be able to suppress glucose production and increase glucose utilization in response to increased exogenous glucose. The second objective of this study is to determine if exogenous insulin, with serum glucose levels held relatively constant, will suppress endogenous glucose production and increase glucose utilization.